This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Primary Aims: 1. To determine the switch rate into hypomania or mania when treating patients with BD II depression with SSRI antidepressant (sertraline) monotherapy, mood stabilizer (lithium) monotherapy or the combination (lithium plus sertraline). 2. To assess the relative tolerability (side effects rate) of sertraline monotherapy vs. lithium monotherapy or the combination. 3. To determine good outcome rates defined as good antidepressant response without manic switch or unacceptable side effects.